My authentication application in adroid studio always marks failed authentication

I already have my application but because more than I put the correct username and password it tells me that it is invalid, and this code had already done it before and if it worked, I do not know what I'm doing wrong

    package com.example.medin.cofa;
    import android.content.Intent;
    import android.support.annotation.NonNull;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.Toast;
    import com.google.android.gms.tasks.OnCompleteListener;
    import com.google.android.gms.tasks.Task;
    import com.google.firebase.auth.AuthResult;
    import com.google.firebase.auth.FirebaseAuth;
    import com.google.firebase.auth.FirebaseUser;

    public class MainActivity extends AppCompatActivity {
    private Button btn_ingresar;
    private EditText et_pass,et_usuario;
    public final static String extra= "usuario";

    private FirebaseAuth mAuth;
    private FirebaseAuth.AuthStateListener mAuthListener;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        btn_ingresar= (Button)findViewById(R.id.button);
        et_pass=(EditText)findViewById(R.id.editText_pass);
        et_usuario= (EditText)findViewById(R.id.editText_usuario);

        btn_ingresar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mAuth.signInWithEmailAndPassword(et_usuario.getText().toString(), et_pass.getText().toString())
                        .addOnCompleteListener(MainActivity.this, new OnCompleteListener<AuthResult>() {
                            @Override
                            public void onComplete(@NonNull Task<AuthResult> task) {
                              //  Log.d(TAG, "signInWithEmail:onComplete:" + task.isSuccessful());

                                // If sign in fails, display a message to the user. If sign in succeeds
                                // the auth state listener will be notified and logic to handle the
                                // signed in user can be handled in the listener.
                                if (!task.isSuccessful()) {
                                    //Log.w(TAG, "signInWithEmail:failed", task.getException());
                                    Toast.makeText(MainActivity.this,"Autentificacion Fallada.",
                                            Toast.LENGTH_SHORT).show();
                                }

                                // ...
                            }
                        });

            }
        });

        mAuth = FirebaseAuth.getInstance();
        mAuthListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                FirebaseUser user = firebaseAuth.getCurrentUser();
                if (user != null) {
                    Intent segundo = new Intent(MainActivity.this,Main2Activity.class);
                    segundo.putExtra(extra,user.getEmail());
                    startActivity(segundo);
                    // User is signed in
                   // Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
                } else {
                    // User is signed out
                    //Log.d(TAG, "onAuthStateChanged:signed_out");
                }
                // ...
            }
        };


    }
    @Override
    public void onStart() {
        super.onStart();
        mAuth.addAuthStateListener(mAuthListener);
    }
    @Override
    public void onStop() {
        super.onStop();
        if (mAuthListener != null) {
            mAuth.removeAuthStateListener(mAuthListener);
        }
    }
}